It is well known that backing up a vehicle with a trailer for many drivers is often difficult and frustrating. Even individuals with considerable driving experience often have little opportunity to develop the skill required to back up a trailer. Much of the difficulty associated with backing up a trailer results from the fact that it is not intuitive for many drivers to sense the jackknifing situation before it is too late a nd from the fact that many drivers do not know how to steer properly in order to align the trailer back to avoid a jackknifing situation. It is the purpose of this invention to provide such assistance to the driver by the early detection of vehicle-trailer jackknifing tendency and provide steering direction assistance to avoid a jackknifing situation.
In general, vehicle-trailer backing up is by nature an unstable motion, unless an experienced driver in the loop stabilizes it with timely and proper steering and/or braking. Jackknife occurs when a vehicle-trailer is approaching away from its equilibrium position, a position intended by the driver through his/her steering input, and thus becomes unstable. In other words, the relative angle between vehicle and trailer is diverging from the driver's intended target angle, and usually increases if proper steering and/or braking action are not taken. This is typically out of control by the driver, either due to lack of sufficient driving skill, or the condition is too severe. Therefore, a driver's capability in controlling the motion of vehicle-trailer combination is one of the key elements in this invention.
The prior art can be found through U.S. Pat. No. 6,268,800 and U.S. Pat. No. 5,912,626 related to this invention. Both of these systems use hitch articulation position as the sole criteria to detect a potential jackknifing situation. While systems provide satisfactory functioning for a vehicle towing a trailer, they may not function during the backing up of a trailer. More particularly, neither of them takes into account the operator and vehicle-trailer combination into consideration. Furthermore the articulation rate (as how fast the jackknife is to happen) during the detection of jackknife situation is not used in their calculations.